1. Field of the Invention
The present invention relates to portable, hand-held shock producing devices which can be used as prods for livestock or for controlling crowds and the like.
2. Discussion of Related Art
Electric shock prods are generally hand-held devices that are thrust axially and sometimes laterally against the subject, usually human or animal, to apply an electric shock. Every prod contains a housing which provides a handle or other holding fixture and contains the electrical components of the device. Every prod also provides some prescribed separation or extension between the operator and the point of electrode-to-subject contact. Prior prod designs can be placed in one of the following categories:
(1) The configuration shown in FIGS. 1 and 2 which comprises a component housing and the prod extension combined in one structure such as tube 2. Insulator 5 covers the end of the tube from which electrodes 6 and 7 extend. For component preservation, the tube 2 must be rigid and not subject to significant deformation or deflection. Furthermore, the cross-section of tube 2 must be large enough to house the components which include batteries. Tube 2 usually has an internal diameter on the order of 3/4 inch to one inch and a thickness usually on the order of 1/32 inch. A typical prod with a one inch I.D. and 0.035 inch thick wall can be shown by basic strength formulas to have a bending moment of well over 200 foot-pounds. Such a prod is very hazardous to the operator if the prod were to become wedged between, for example, a fence post and a large moving animal. The 200 foot-pound strength is sufficient to throw a man or cause him to lose control and drop the prod. Additionally, the extended center of gravity, shown at 3, of such a prod assembly makes the prod extremely unwieldy. With a typical 12 inches between the handle 1 and the center of gravity 3, the torque exerted through the operator's hand is unacceptable. Examples of patents which disclose prods similar to that shown in FIGS. 1 and 2 are: U.S. Pat. Nos. 3,998,459 to Henderson; 3,917,268 to Tingey; 2,441,819 to Haffner; and 2,204,041 to Jefferson.
(2) The most practical and popular prod designs available today are represented by the prod shown in FIGS. 3 and 4 in which the handle 11 is integral with the electrical component housing 10. A separate prod extension pole 14 is connected to the housing 10. Consequently, the design of the prod extension pole 14 is not compromised by the component-housing requirements. The prod extension pole 14 is usually a round fiberglass pole approximately 3/8 inch in diameter containing two conductors 18, 19 connected to the electrodes 16, 17 which are secured by a plastic fixture 15. A simplified collet-chuck arrangement 13 secures the cantilevered extension pole 14 to the main housing. A comfortable balance can be achieved with the center of gravity 12 usually located close to the handle grip area. Replaceable extensions of various lengths are generally available. This type of prod design can be seen in U.S. Design Pat. No. 175,158.
Some designs electrify the periphery of the rigid portion of the electrode mounting by use of appropriately spaced conductors. As seen in U.S. Pat. No. 2,981,465 to Bartel, such electrode extensions are helically wound around the rigid electrode head. The prod otherwise is similar to that shown in FIG. 2. Another example of exposed peripheral electrodes can be seen in U.S. Pat. No. 3,819,108 to Jordan. In Jordan, conductors are located about the periphery of a rigid cylindrical pole or stick which is similar in construction to the tubular body of FIG. 1. U.S. Pat. No. 3,119,554 to Fagan et al shows another example of external electrodes used on an electric shock prod. In Fagan et al, the conductors are located axially along the periphery of an insulating rod.
U.S. Pat. No. 2,561,122 to Juergens shows a highly resilient coupling used between the prod pole extension and the housing/handle. The coupling is analagous to the well-known coil-spring vehicular antenna mounts. Such a spring coupling is functional for simple lateral loads applied near the free end of the pole. However, bending moments or lateral loads near the resilient mounting could result in severe lateral deflection of the mounting, which deflection is restrained ultimately only by the strength of the mounting or the pole. In other words, the resilient coupling would not stop the pole or other prod parts from breaking in the presence of loads or torques which tend to cause extreme lateral excursions of the couplings.
U.S. Pat. No. 4,006,390 to Levine shows a prod assembly with an extendable electrode. Several mechanisms are used for extending the electrode including a pneumatically-actuated rolled tube which is similar to a "blow-out" party favor and a self-unwinding preformed spring web or strip in which the unwinding portion forms a thin-walled cylindrical type tube. The inherent weakness of such extendable beam designs is limited lateral rigidity. Lateral impacts easily cause local buckling deformation or rupture of the thin-walled extendable shells. This characteristic lack of flexural rigidity results in the inability to survive slashing or whipping strokes which are unavoidable in any hostile environment.
U.S. Pat. No. 3,227,362 shows an electric slapper prod. The electrode extension is in the form of a flat belt-like or razor-strap-like assembly of pliable material such as fabric or leather with embedded flexible wires running lengthwise to two laterally, not axially, projecting screws which serve as electrode tips. This invention is characterized by its construction from high plasticity materials with a consequent lack of lateral and axial flexural rigidity. Accordingly, the device is used strictly for slapping. Useful extension of the slapper occurs only as a result of the tensile load imposed by centrifugal or inertial forces caused by the rotating or swinging action of the operator's hand.
Various major problems are inherent in known prod assemblies. For instance, with reference to FIGS. 2 and 3, fiberglass prod extensions 14 tend to snap frequently. This is due to the fact, as shown by basic structural deflection formulas, that the minimum bending radius which can be attained before fracture for a 3/8-inch diameter polyester fiberglass pole is approximately 17 inches. Thus, it is obvious that a prod extension would necessarily snap when caught in a tight squeeze between, for example, an animal and a loading chute. Also, the electrode fixture 15 and electrodes 16 and 17 are subject to extreme bending loads during routine encounters with the ground and other objects. Typical brass electrode pins 3/16 inch diameter by one inch in length are frequently bent by the impacts encountered which in turn usually fractures the plastic electrode fixture 15. Further, the torque exerted by the typical prod extension pole is on the order of 210 inch-pounds when flexed to near its limit. This torque applies up to 300 pounds of force to the small area of contact within a typical plastic chuck assembly 13. This kind of cantilever coupling is not capable of reliably withstanding the bending moments applied and thus often fractures.
Switch constructions in electric prods are also a problem. On-off switching in electric prods of the FIG. 1 configuration is often accomplished by axial pressure against the subject which depresses either the electrode assembly 5 or the tube 2 so as to close switch contacts. This type of switch construction is impractical in realistic environments of, for example, livestock processing, where debris quickly clog telescoping fittings or switches. The on-off switch in a design similar to FIG. 2 is usually located under the handle portion 11 for easy access by the index finger. With no wraparound shield, the switch and any additional items such as a charger connector are fully exposed to dirt and impact breakage, although to a lesser extent than is characteristic in designs similar to FIG. 1.
Also, on-off switches, particularly in the current fed induction coil high-voltage generators used in electric prods, are subject to high-voltage arcing and consequent contact destruction at the instant the switch is turned off, and during contact bounce periods. This is related to the voltage generated when current feeding a charging inductance is cut off. Depending upon transient conditions prevailing in an oscillating inductance-charging circuit when the switch contacts are opened, the voltage spikes appearing across the switch terminals may be of either or both polarities and, unchecked, can reach several hundred volts. Prior prod devices have done nothing to suppress this arcing.